Offshore_technology

1. Introduction
2. Size and configuration
3. Support structure
4. Standards
5. Project Experience
6. Operation and maintenance
7. Electrical
8. general REFERENCES



1 Introduction

This Work Package brings together current work from each of the member countries to help identify future strategies for adoption by the European Offshore Wind Industry.

With this objective, within this state of the art summary, the following issues are addressed:

* Recent and current research

* Recent and current projects and national plans

* Market developments

* Benefits to the environment

* Employment prospects for Europe

* Benefits for European Industry

Members of the Concerted Action have responded to questionnaires addressing these points. This document consolidates the responses and provides references for more detailed information.

The current activities in offshore wind energy are built on the experiences of two fields of engineering: those of wind energy and of offshore il and gas, with smaller but significant input from the field of coastal engineering. Wind energy has a history that stretches back about a thousand years, with one of the first records of windturbines being from the mid tenth century, a reference to vertical axis windturbines in Afghanistan; the horizontal axis type first appeared a couple of centuries later in Northern Europe and quickly became a common sight. The wind energy industry as we know it today, really began in the early Seventies, when the oil price shock caused many governments around the world set?research programmes to investigate power generation technology from non-oil dependent sources, including wind energy. However, once the oil price stabilised, these research programmes were curtailed and no commercial plants were in fact built in this short period. The second oil price shock in the late seventies revitalised the efforts and led to commercial developments, such as the large fields of wind-turbines in California. This second boom drew in many established companies and encourage entrepreneurs to set up new enterprises, some of which persist as the big names of today. Many of the windturbines installed in the States in the mid-Eighties were manufactured in that country but Europe also supplied large number of them. When the supply of new projects in California dried up, most of these companies folded or closed their windenergy operations; the exception was in Denmark, where wind farm development persisted, albeit at a much lower pace, enabling a handful of Danish companies to survive and later thrive when the threat of environmental pollution and global-warming caused the current boom in wind energy.

The offshore Industry, which has grown up around the hydrocarbon reserves in the North Sea, is much more recent, with the first discovery in the British sector having been made in the Sixties. Since then, regular high prices for oil and incremental technological developments have allowed the Industry to exports ever deeper and more hostile waters, in fact significantly more hostile than the seas where the current offshore wind farms are being built.

The first ideas for generating electricity using wind in the offshore environment where in the late seventies and numerous feasibility studies where undertaken in the following decayed. It was only in the early nineties that the first prototype offshore wind farms were actually built: at Vindeby in Denmark in 1991 and a single turbine at Nogersund, Sweden in the same year. The performance of the wind farm at Vindeby has been heavily monitored and evaluated and much useful knowledge has been gained on the performance of windturbines offshore but also on the performance of wind turbine in general (specifically because of the low turbulence conditions). The windfarm consisted of 11 windturbines, rated at 450 kW, giving a total farm output off almost 5 MW; by way of illustration of the progress made in this industry, the largest single prototype wind-turbines currently being installed have the same rated power as that whole windfarm. Vindeby is located in a relatively protected part of the Baltic Sea, surrounded by islands but even there access has been a problem because of excessively high waves.

Vindeby was soon joined by a second wind farm in Denmark, at Tuno KnÝb, and two further windfarms were built in the Dutch inland lake of IJsselmeer, at Lely / Medemblik and Dronten. These were built on monopiles, which is becoming the preferred support structure for offshore windturbines. In the latter half of the last decade, there was less activity, with a single windfarm being built at Bockstigen-Valor in Sweden. The first years of this millennium have seen new windfarms constructed using large multi-megwatt windturbines; the largest is that Middelgrunden and is clearly visible from Copenhagen. It consists of 20 turbine each rated at 2 MW is located on concrete gravity bases; the wind farm at Blyth consists of only two turbine again each of 2 MW, however they are located in the harshest environment yet: the North East coast of England facing directly into the North Sea. Two wind farms have also been built in Swedish waters, at Utgrunden (in 2000) and Yttre Stengrund (in 2001) and now four wind turbine manufacturers have experience of building and operating large wind-turbines for offshore operation, which surely must give confidence for success of the projects over the coming years.

The construction of offshore wind farms has also been built on the activities of sympathetic politicians and civil servants, researchers and environmentalists. The field of tertiary education is now also becoming more active, with masters courses in wind energy or general renewable energy at universities in several European countries. The main body of this report attempts to give details of the more important of all these activities.

Webcontent © 2002 www.offshorewindenergy.org
Updated September 2008